text: /*
   * Copyright (c) 2017 - 2018, Nordic Semiconductor ASA
   *
   * SPDX-License-Identifier: Apache-2.0
   */
  
  #include <spi.h>
  #include <nrfx_spi.h>
  
  #define LOG_DOMAIN "spi_nrfx_spi"
  #define LOG_LEVEL CONFIG_SPI_LOG_LEVEL
  #include <logging/log.h>
  LOG_MODULE_REGISTER(spi_nrfx_spi);
  
  #include "spi_context.h"
  
  struct spi_nrfx_data {
  	struct spi_context ctx;
  	size_t chunk_len;
  	bool   busy;
  };
  
  struct spi_nrfx_config {
  	nrfx_spi_t spi;
  };
  
  static inline struct spi_nrfx_data *get_dev_data(struct device *dev)
  {
  	return dev->driver_data;
  }
  
  static inline const struct spi_nrfx_config *get_dev_config(struct device *dev)
  {
  	return dev->config->config_info;
  }
  
  static inline nrf_spi_frequency_t get_nrf_spi_frequency(u32_t frequency)
  {
  	/* Get the highest supported frequency not exceeding the requested one.
  	 */
  	if (frequency < 250000) {
  		return NRF_SPI_FREQ_125K;
  	} else if (frequency < 500000) {
  		return NRF_SPI_FREQ_250K;
  	} else if (frequency < 1000000) {
  		return NRF_SPI_FREQ_500K;
  	} else if (frequency < 2000000) {
  		return NRF_SPI_FREQ_1M;
  	} else if (frequency < 4000000) {
  		return NRF_SPI_FREQ_2M;
  	} else if (frequency < 8000000) {
  		return NRF_SPI_FREQ_4M;
  	} else {
  		return NRF_SPI_FREQ_8M;
  	}
  }
  
  static inline nrf_spi_mode_t get_nrf_spi_mode(u16_t operation)
  {
  	if (SPI_MODE_GET(operation) & SPI_MODE_CPOL) {
  		if (SPI_MODE_GET(operation) & SPI_MODE_CPHA) {
  			return NRF_SPI_MODE_3;
  		} else {
  			return NRF_SPI_MODE_2;
  		}
  	} else {
  		if (SPI_MODE_GET(operation) & SPI_MODE_CPHA) {
  			return NRF_SPI_MODE_1;
  		} else {
  			return NRF_SPI_MODE_0;
  		}
  	}
  }
  
  static inline nrf_spi_bit_order_t get_nrf_spi_bit_order(u16_t operation)
  {
  	if (operation & SPI_TRANSFER_LSB) {
  		return NRF_SPI_BIT_ORDER_LSB_FIRST;
  	} else {
  		return NRF_SPI_BIT_ORDER_MSB_FIRST;
  	}
  }
  
  static int configure(struct device *dev,
  		     const struct spi_config *spi_cfg)
  {
  	struct spi_context *ctx = &get_dev_data(dev)->ctx;
  	const nrfx_spi_t *spi = &get_dev_config(dev)->spi;
  
  	if (spi_context_configured(ctx, spi_cfg)) {
  		/* Already configured. No need to do it again. */
  		return 0;
  	}
  
  	if (SPI_OP_MODE_GET(spi_cfg->operation) != SPI_OP_MODE_MASTER) {
  		LOG_ERR("Slave mode is not supported on %s",
  			    dev->config->name);
  		return -EINVAL;
  	}
  
  	if (spi_cfg->operation & SPI_MODE_LOOP) {
  		LOG_ERR("Loopback mode is not supported");
  		return -EINVAL;
  	}
  
  	if ((spi_cfg->operation & SPI_LINES_MASK) != SPI_LINES_SINGLE) {
  		LOG_ERR("Only single line mode is supported");
  		return -EINVAL;
  	}
  
  	if (SPI_WORD_SIZE_GET(spi_cfg->operation) != 8) {
  		LOG_ERR("Word sizes other than 8 bits"
  			    " are not supported");
  		return -EINVAL;
  	}
  
  	if (spi_cfg->frequency < 125000) {
  		LOG_ERR("Frequencies lower than 125 kHz are not supported");
  		return -EINVAL;
  	}
  
  	ctx->config = spi_cfg;
  	spi_context_cs_configure(ctx);
  
  	nrf_spi_configure(spi->p_reg,
  			  get_nrf_spi_mode(spi_cfg->operation),
  			  get_nrf_spi_bit_order(spi_cfg->operation));
  	nrf_spi_frequency_set(spi->p_reg,
  			      get_nrf_spi_frequency(spi_cfg->frequency));
  
  	return 0;
  }
  
  static void transfer_next_chunk(struct device *dev)
  {
  	struct spi_nrfx_data *dev_data = get_dev_data(dev);
  	struct spi_context *ctx = &dev_data->ctx;
  	int error = 0;
  
  	size_t chunk_len = spi_context_longest_current_buf(ctx);
  
  	if (chunk_len > 0) {
  		nrfx_spi_xfer_desc_t xfer;
  		nrfx_err_t result;
  
  		dev_data->chunk_len = chunk_len;
  
  		xfer.p_tx_buffer = ctx->tx_buf;
  		xfer.tx_length   = spi_context_tx_buf_on(ctx) ? chunk_len : 0;
  		xfer.p_rx_buffer = ctx->rx_buf;
  		xfer.rx_length   = spi_context_rx_buf_on(ctx) ? chunk_len : 0;
  		result = nrfx_spi_xfer(&get_dev_config(dev)->spi, &xfer, 0);
  		if (result == NRFX_SUCCESS) {
  			return;
  		}
  
  		error = -EIO;
  	}
  
  	spi_context_cs_control(ctx, false);
  
  	LOG_DBG("Transaction finished with status %d", error);
  
  	spi_context_complete(ctx, error);
  	dev_data->busy = false;
  }
  
  static int transceive(struct device *dev,
  		      const struct spi_config *spi_cfg,
  		      const struct spi_buf_set *tx_bufs,
  		      const struct spi_buf_set *rx_bufs)
  {
  	struct spi_nrfx_data *dev_data = get_dev_data(dev);
  	int error;
  
  	error = configure(dev, spi_cfg);
  	if (error == 0) {
  		dev_data->busy = true;
  
  		spi_context_buffers_setup(&dev_data->ctx, tx_bufs, rx_bufs, 1);
  		spi_context_cs_control(&dev_data->ctx, true);
  
  		transfer_next_chunk(dev);
  
  		error = spi_context_wait_for_completion(&dev_data->ctx);
  	}
  
  	spi_context_release(&dev_data->ctx, error);
  
  	return error;
  }
  
  static int spi_nrfx_transceive(struct device *dev,
  			       const struct spi_config *spi_cfg,
  			       const struct spi_buf_set *tx_bufs,
  			       const struct spi_buf_set *rx_bufs)
  {
  	spi_context_lock(&get_dev_data(dev)->ctx, false, NULL);
  	return transceive(dev, spi_cfg, tx_bufs, rx_bufs);
  }
  
  #ifdef CONFIG_SPI_ASYNC
  static int spi_nrfx_transceive_async(struct device *dev,
  				     const struct spi_config *spi_cfg,
  				     const struct spi_buf_set *tx_bufs,
  				     const struct spi_buf_set *rx_bufs,
  				     struct k_poll_signal *async)
  {
  	spi_context_lock(&get_dev_data(dev)->ctx, true, async);
  	return transceive(dev, spi_cfg, tx_bufs, rx_bufs);
  }
  #endif /* CONFIG_SPI_ASYNC */
  
  static int spi_nrfx_release(struct device *dev,
  			    const struct spi_config *spi_cfg)
  {
  	struct spi_nrfx_data *dev_data = get_dev_data(dev);
  
  	if (!spi_context_configured(&dev_data->ctx, spi_cfg)) {
  		return -EINVAL;
  	}
  
  	if (dev_data->busy) {
  		return -EBUSY;
  	}
  
  	spi_context_unlock_unconditionally(&dev_data->ctx);
  
  	return 0;
  }
  
  static const struct spi_driver_api spi_nrfx_driver_api = {
  	.transceive = spi_nrfx_transceive,
  #ifdef CONFIG_SPI_ASYNC
  	.transceive_async = spi_nrfx_transceive_async,
  #endif
  	.release = spi_nrfx_release,
  };
  
  
  static void event_handler(const nrfx_spi_evt_t *p_event, void *p_context)
  {
  	struct device *dev = p_context;
  	struct spi_nrfx_data *dev_data = get_dev_data(dev);
  
  	if (p_event->type == NRFX_SPI_EVENT_DONE) {
  		spi_context_update_tx(&dev_data->ctx, 1, dev_data->chunk_len);
  		spi_context_update_rx(&dev_data->ctx, 1, dev_data->chunk_len);
  
  		transfer_next_chunk(dev);
  	}
  }
  
  static int init_spi(struct device *dev, const nrfx_spi_config_t *config)
  {
  	/* This sets only default values of frequency, mode and bit order.
  	 * The proper ones are set in configure() when a transfer is started.
  	 */
  	nrfx_err_t result = nrfx_spi_init(&get_dev_config(dev)->spi,
  					  config,
  					  event_handler,
  					  dev);
  	if (result != NRFX_SUCCESS) {
  		LOG_ERR("Failed to initialize device: %s",
  			    dev->config->name);
  		return -EBUSY;
  	}
  
  	spi_context_unlock_unconditionally(&get_dev_data(dev)->ctx);
  
  	return 0;
  }
  
  #define SPI_NRFX_SPI_DEVICE(idx)					       \
  	static int spi_##idx##_init(struct device *dev)			       \
  	{								       \
  		IRQ_CONNECT(NRFX_IRQ_NUMBER_GET(NRF_SPI##idx),		       \
  			    DT_NORDIC_NRF_SPI_SPI_##idx##_IRQ_PRIORITY,	       \
  			    nrfx_isr, nrfx_spi_##idx##_irq_handler, 0);	       \
  		const nrfx_spi_config_t config = {			       \
  			.sck_pin   = DT_NORDIC_NRF_SPI_SPI_##idx##_SCK_PIN,    \
  			.mosi_pin  = DT_NORDIC_NRF_SPI_SPI_##idx##_MOSI_PIN,   \
  			.miso_pin  = DT_NORDIC_NRF_SPI_SPI_##idx##_MISO_PIN,   \
  			.ss_pin    = NRFX_SPI_PIN_NOT_USED,		       \
  			.orc       = CONFIG_SPI_##idx##_NRF_ORC,	       \
  			.frequency = NRF_SPI_FREQ_4M,			       \
  			.mode      = NRF_SPI_MODE_0,			       \
  			.bit_order = NRF_SPI_BIT_ORDER_MSB_FIRST,	       \
  		};							       \
  		return init_spi(dev, &config);				       \
  	}								       \
  	static struct spi_nrfx_data spi_##idx##_data = {		       \
  		SPI_CONTEXT_INIT_LOCK(spi_##idx##_data, ctx),		       \
  		SPI_CONTEXT_INIT_SYNC(spi_##idx##_data, ctx),		       \
  		.busy = false,						       \
  	};								       \
  	static const struct spi_nrfx_config spi_##idx##_config = {	       \
  		.spi = NRFX_SPI_INSTANCE(idx),				       \
  	};								       \
  	DEVICE_AND_API_INIT(spi_##idx, DT_NORDIC_NRF_SPI_SPI_##idx##_LABEL,    \
  			    spi_##idx##_init,				       \
  			    &spi_##idx##_data,				       \
  			    &spi_##idx##_config,			       \
  			    POST_KERNEL, CONFIG_SPI_INIT_PRIORITY,	       \
  			    &spi_nrfx_driver_api)
  
  #ifdef CONFIG_SPI_0_NRF_SPI
  SPI_NRFX_SPI_DEVICE(0);
  #endif
  
  #ifdef CONFIG_SPI_1_NRF_SPI
  SPI_NRFX_SPI_DEVICE(1);
  #endif
  
  #ifdef CONFIG_SPI_2_NRF_SPI
  SPI_NRFX_SPI_DEVICE(2);
  #endif
  